This invention relates to an end seal structure for a cable closure, and more particularly to an end seal structure for a cable closure for protectively receiving a cable connection section at which connection or splicing, branching and wiring of communication cables such as optical fiber cables, metal cables or the like are carried out.
In general, a cable connection apparatus includes a receiving box for protectively enclosing a connection section of cables. The receiving box includes a vertically splittable cylindrical casing and end sections arranged on opposite ends of the cylindrical casing to close the casing. The cables are inserted through the end sections of the receiving box into the casing. The cylindrical casing is formed by securely connecting casing halves to each other using a fixing means while abutting parting faces of the casing halves against each other to airtightly or water-tightly hold the cable connection section including connectors in the cylindrical casing.
The end sections of the receiving box of the cable connection apparatus function to permit a cable, a support wire, an aerial cable and a trunk cable to be inserted therethrough to the cable connection section. For this purpose, the end section is formed with insertion holes. Such an end section of one type is so constructed that when a cable of a reduced diameter is inserted through one of such insertion holes previously provided through the end section and formed to have a size corresponding to a maximum diameter of cables applied, a suitable spacer or bushing is arranged in a gap formed between the insertion hole of the end section and the cable or a rubber tape of a predetermined thickness is wound on the cable having a reduced diameter, resulting in the gap being closed or filled up. This permits secure fitting of the cable in the end section. Additionally, a sealing tape of may be wound on the cable, to thereby ensure airtightness or water-tightness of the end section. An end section of another type is constructed in such a manner that tapered cylinders are provided on the end section so as to be cut in situ at predetermined portions thereof depending on diameters of cables applied. In either case, the end section is joinedly fixed at a predetermined portion thereof to the cable by means of a sealing tape, a PVC tape or the like.
As described above, in such conventional techniques of airtightly or water-tightly sealing the insertion holes for various cables different in diameter, a rubber tape, a sealing tape or the like is wound on an outer periphery of the cable to sealedly close the gap between the cable and the insertion hole. However, such a winding operation is troublesome. In particular, removal of the sealing tape and replacement thereof during installation of a new additional cable or maintenance of the cable are highly troublesome.
For example, an optical fiber cable includes a sheath having a support wire arranged in association with optical fibers and integrally covered together with connection elements or neck sections. Thus, separation of the connection element from the optical fiber cable by cutting causes the connection element to remain in the form of a strip-like projection or protrusion on the sheath of the optical fiber cable and the support wire, so that the strip-like projection often deteriorates sealing between the cable and the cable insertion hole when the cable is inserted through the insertion hole. Thus, winding of the sealing tape on the cable fails to effectively close or fill up a gap formed between the cable or support wire and the cable insertion hole, so that complete removal of the strip-like projection which is highly troublesome is necessarily required, leading to a deterioration in workability. Also, the cable to be applied is substantially varied in diameter, so that replacement of the tapered end section, rubber tape and the like is required, leading to time-consumption and an increase in repair cost.
Further, when the cable to be applied is a metal cable formed in a strand by twisting a number of metal wires together, it is formed on an outer periphery thereof with ruggedness, which causes gaps to occur between the cable and the insertion hole, leading to a deterioration in sealing function of the end seal structure in spite of use of the taping.
In addition, arrangement of the spacer or bushing between the cable and the cable insertion hole requires to prepare a number of spacers or bushings formed with cable insertion holes different in size so as to be accommodated to cables different in diameter.